Devices and Methods for Duplexer Loss Reduction
Methods and devices are described for reducing transmit RF signal loss in a bi-directional RF transmit/receive system with a duplexer circuit. In one case a filter in a transmit path is used such as to reduce amplified noise in a receive frequency band.
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The present application is related to U.S. patent application Ser. No. ______ entitled “Methods for Increasing RF Throughput Via Usage of Tunable Filters” (Attorney Docket No. PER-099-PAP) filed on even date herewith and incorporated herein by reference in its entirety. The present application is also related to U.S. patent application Ser. No. ______ entitled “Integrated Tunable Filter Architecture” (Attorney Docket No. PER-115-PAP) filed on even date herewith and incorporated herein by reference in its entirety.
The present application may be related to U.S. patent application Ser. No. 13/797,779 entitled “Scalable Periphery Tunable Matching Power Amplifier”, filed on Mar. 3, 2013, the disclosure of which is incorporated herein by reference in its entirety. The present application may also be related to International Application No. PCT/US2009/001358, entitled “Method and Apparatus for use in digitally tuning a capacitor in an integrated circuit device”, filed on Mar. 2, 2009, the disclosure of which is incorporated herein by reference in its entirety. The present application may also be related to U.S. patent application Ser. No. 13/595,893, entitled “Method and Apparatus for Use in Tuning Reactance in a Circuit Device”, filed on Aug. 27, 2012, the disclosure of which is incorporated herein by reference in its entirety. The present application may also be related to U.S. patent application Ser. No. 14/042,312, filed on Sep. 30, 2013, entitled “Methods and Devices for Impedance Matching in Power Amplifier Circuits”, the disclosure of which is incorporated herein by reference in its entirety. The present application may also be related to U.S. Pat. No. 7,248,120, issued on Jul. 24, 2007, entitled “Stacked Transistor Method and Apparatus”, the disclosure of which is incorporated herein by reference in its entirety. The present application may also be related to U.S. patent application Ser. No. 13/828,121, filed on Mar. 14, 2013, entitled “Autonomous Power Amplifier Optimization”, the disclosure of which is incorporated herein by reference in its entirety. The present application may also be related to U.S. patent application Ser. No. 13/967,866 entitled “Tunable Impedance Matching Network”, filed on Aug. 15, 2013, the disclosure of which is incorporated herein by reference in its entirety. The present application may also be related to U.S. patent application Ser. No. 13/797,686 entitled “Variable Impedance Match and Variable Harmonic Terminations for Different Modes and Frequency Bands”, filed on Mar. 12, 2013, the disclosure of which is incorporated herein by reference in its entirety. The present application may also be related to U.S. patent application Ser. No. 14/042,331 entitled “Methods and Devices for Thermal Control in Power Amplifier Circuits”, filed on Sep. 30, 2013, the disclosure of which is incorporated herein by reference in its entirety. The present application may also be related to U.S. patent application Ser. No. 13/829,946 entitled “Amplifier Dynamic Bias Adjustment for Envelope Tracking, filed on Mar. 14, 2013, the disclosure of which is incorporated herein by reference in its entirety. The present application may also be related to US patent application Ser. No. 13/830,555 entitled “Control Systems and Methods for Power Amplifiers Operating in Envelope Tracking Mode”, filed on Mar. 14, 2013, the disclosure of which is incorporated herein in its entirety.
BACKGROUND1. Field
The present teachings relate to RF (radio frequency) circuits. More particularly, the present teachings relate to methods and apparatuses for reducing duplexer loss in an RF transmit path.
2. Description of Related Art
Radio frequency (RF) devices, such as cell phone transmitters, are becoming increasingly complex due to additional frequency bands, more complex modulation schemes, higher modulation bandwidths, and the introduction of data throughput improvement schemes such as simultaneous RF transmission and/or reception within a same or different, but closely spaced, bands or channels within a band (e.g. voice, data), and aggregate transmission wherein information is multiplexed over parallel RF transmissions. Due to the closely spaced transmit/receive frequency bands/channels of a front-end stage used in such RF devices, burden on a duplexer design used in such RF devices has increased, where associated sharp band-pass filters can isolate an RF signal being transmitted from a receive path at the cost of attenuating the RF signal being transmitted.
SUMMARYAccording to a first aspect of the present disclosure, a radio frequency (RF) circuital arrangement is presented, the arrangement comprising: an RF transmit path comprising: a plurality of cascaded amplifiers configured, during operation of the circuital arrangement, to amplify a transmit RF signal, the transmit RF signal operating over a first frequency band, and a first filter placed between two consecutive amplifiers of the plurality of cascaded amplifiers, the first filter configured during operation of the circuital arrangement, to attenuate a second frequency hand different from the first frequency band, and pass the first frequency band; an RF receive path configured, during operation of the circuital arrangement, to receive a receive RF signal over the second frequency band, and a bi-directional transmit/receive circuit connected to the RF transmit path and to the RF receive path, the bi-directional transmit/receive circuit comprising: a second filter configured, during operation of the circuital arrangement, to pass the first frequency band and to attenuate the second frequency band.
According to second aspect of the present disclosure, a method for reducing loss of a transmit RF signal in a duplexer unit of an radio frequency (RF) transmit/receive system, the method comprising: providing an RF transmit path comprising a plurality of cascaded amplifiers; inserting, in-between two amplifiers of the plurality of cascaded amplifiers, a first filter; based on the inserting, attenuating a receive frequency band and passing a transmit frequency band; based on the attenuating, relaxing design parameters of a second filter of a duplexer unit, the second filter being configured to pass the transmit frequency band and to attenuate the receive frequency band; based on the relaxing, reducing a number of filter stages of the second filter, and based on the reducing, reducing an attenuation at the transmit frequency band through the second filter of the duplexer unit.
The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more embodiments of the present disclosure and, together with the description of example embodiments, serve to explain the principles and implementations of the disclosure.
Throughout this description, embodiments and variations are described for the purpose of illustrating uses and implementations of the inventive concept. The illustrative description should be understood as presenting examples of the inventive concept, rather than as limiting the scope of the concept as disclosed herein.
The present disclosure describes electrical circuits in electronics devices (e.g., cell phones, radios) having a plurality of devices, such as for example, transistors (e.g., MOSFETs). Persons skilled in the art will appreciate that such electrical circuits comprising transistors can be arranged as amplifiers. As described in a previous disclosure (U.S. patent application Ser. No. 13/797,779, incorporated herein by reference in its entirety), a plurality of such amplifiers can be arranged in a so-called “scalable periphery” (SP) architecture of amplifiers where a total number (e.g., 64) of amplifier segments are provided. Depending on the specific requirements of an application, the number of active devices (e.g., 64, 32, etc.), or a portion of the total number of amplifiers (e.g. 1/64, 2/64, 40% of 64, etc. . . . ), can be changed for each application. For example, in some instances, the electronic device may desire to output a certain amount of power, which in turn, may require 32 of 64 SP amplifier segments to be used. In yet another application of the electronic device, a lower amount of output power may be desired, in which case, for example, only 16 of 64 SP amplifier segments are used. According to some embodiments, the number of amplifier segments used can be inferred by a nominal desired output power as a function of the maximum output power (e.g. when all the segments are activated). For example, if 30% of the maximum output power is desired, then a portion of the total amplifier segments corresponding to 30% of the total number of segments can be enabled. The scalable periphery amplifier devices can be connected to corresponding impedance matching circuits. The number of amplifier segments of the scalable periphery amplifier device that are turned on or turned off at a given moment can be according to a modulation applied to an input RF signal, a desired output power, a desired linearity requirement of the amplifier or any number of other requirements.
The term “amplifier” as used in the present disclosure is intended to refer to amplifiers comprising single or stacked transistors configured as amplifiers, and can be used interchangeably with the term “power amplifier (PA)”. Such terms can refer to a device that is configured to amplify a signal input to the device to produce an output signal of greater magnitude than the magnitude of the input signal. Stacked transistor amplifiers are described for example in U.S. Pat. No. 7,248,120, issued on Jul. 24, 2007, entitled “Stacked Transistor Method and Apparatus”, the disclosure of which is incorporated herein by reference in its entirety. Such amplifier and power amplifiers can be applicable to amplifiers and power amplifiers of any stages (e.g., pre-driver, driver, final), known to those skilled in the art.
As used in the present disclosure, the term “mode” can refer to a wireless standard and its attendant modulation and coding scheme or schemes. As different modes may require different modulation schemes, these may affect required channel bandwidth as well as affect the peak-to-average-ratio (PAR), also referred to as peak-to-average-power-ratio (PAPR), as well as other parameters known to the skilled person. Examples of wireless standards include Global System for Mobile Communications (GSM), code division multiple access (CDMA), Worldwide Interoperability for Microwave Access (WiMAX), Long Term Evolution (LTE), as well as other wireless standards identifiable to a person skilled in the art. Examples of modulation and coding schemes include binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), quadrature amplitude modulation (QAM), 8-QAM, 64-QAM, as well as other modulation and coding schemes identifiable to a person skilled in the art.
As used in the present disclosure, the term “band” can refer to a frequency range. More in particular, the term “band” as used herein refers to a frequency range that can be defined by a wireless standard such as, but not limited to, wideband code division multiple access (WCDMA) and long term evolution (LTE).
As used in the present disclosure, the term “channel” can refer to a frequency range. More in particular, the term “channel” as used herein refers to a frequency range within a band. As such, a band can comprise several channels used to transmit/receive a same wireless standard.
As used in the present disclosure, the term “notch filter” can refer to a band-stop filter, also known as a band-rejection filter or a band-reject filter, with a narrow stopband. Such tilter passes most frequencies unaltered (e.g. without attenuation) and attenuates only those frequencies in a specific frequency range defined by the stopband.
In the circuital arrangement of
The person skilled in the art readily knows that the bi-directional communication system, such as the transmit/receive system (100) of
The person skilled in the art further knows that any electronic device, such as the amplifier (150, 160) of
Noisepower=k·T·B·Fn (1)
where k is the Boltzmann's constant, T is the operating temperature of the device, B is the bandwidth over which the thermal noise is being considered, and Fn is a constant noise factor (figure of merit). Such power associated to the thermal noise, as given by formula (1), at an input of an amplifier, can get amplified via the gain of the amplifier and can therefore produce an amplified noise (e.g. power, voltage) at the output of the amplifier which is a factor of G higher than the noise at the input of the amplifier, G being the gain of the amplifier over the frequency range of interest (e.g. determined by bandwidth B).
Therefore, in a configuration where a cascaded arrangement of amplifiers is used, such as the configuration depicted in
NoiseTotal=N1·G1 . . . Gk+N2·G2 . . . Gk+ . . . +Nk·Gk (2)
where G1 is the gain of the ith amplifier of the cascaded k amplifiers, and N, is the input power associated to the thermal noise at the input of the ith amplifier, as given by formula (1). According to the expression (2), a noise contributed by an amplifier further from the output of the cascaded arrangement of amplifiers (e.g. further from a duplexer) can have a greater impact on the total noise NoiseTotal of the arrangement of cascaded amplifiers, as it gets amplified by a larger number of amplifiers. It should be noted that in the case where an RF signal is fed to such a cascaded arrangement of amplifiers, noise at the output of a corresponding amplifier, such as one in a transceiver unit (105) of
N1=Nxcvr+k·T·B·Fn1 (3)
where Nxcvr is a contributing noise power from the transceiver unit (e.g. 105 of
Therefore, for the particular case of the two-stage cascaded arrangement of
Noise=(Nxcvr+k·T·B·Fdriver)·Gdriver·Gfinal+k·T·B·Ffinal·Gfinal (4)
Such noise can be defined as the transmit channel noise of the transmit/receive system (100) of
A duplexer, such as duplexer (110) of
According to an embodiment of the present disclosure, by inserting a filter (270) (e.g. a band-reject filter, low-pass filter, high-pass filter, notch filter, etc. . . . ), designed to attenuate the receive frequency band centered at the receive center frequency fR, in-between the driver stage (150) and the final stage (160), as depicted in the bi-directional transmit/receive communication system (200) of
Noise=(Nxcvr+k·T·B·Fdriver)·Gdriver·Aint·Gfinal+k·T·B·Ffinal·Gfinal (5)
where Aint is the attenuation provided by the inter-stage (e.g. positioned between two amplification stages of the cascaded arrangement of amplifiers) filter (270) within the receive frequency band.
According to some embodiments of the present disclosure, such attenuation provided by the filter (270) can be in a range of about 10-25 dB (e.g. greater than about 10 dB). The person skilled in the art will appreciate the advantage of lowering such noise (e.g. by greater than about 10 dB) has on the design of the transmit filter (130) which can subsequently be designed with more relaxed design parameters. In turn and according to an embodiment of the present disclosure, a more relaxed transmit filter (130) design can reduce the amount of attenuation within the transmit frequency band (e.g. insertion loss) for an improvement in transmit RF signal power. For example, a typical 2-3 dB insertion loss (e.g. attenuation within the transmit frequency band) provided by a typical transmit filter (130) (e.g. SAW/BAW filter) of a duplexer unit (110) can be reduced to half or to about 1-1.5 dB after relaxing the transmit filter design per the provided embodiment according to the present disclosure. Relaxing of the transmit filter design can in some instances reduce the insertion loss to a value which is less than about 2 dB, and still providing a benefit over the typical larger than about 2 dB insertion loss of a transmit filter (130) implemented using SAW/BAW filters. The person skilled in the art will appreciate the impact of this reduction in terms of a corresponding power amplifier (PA) efficiency, as a 0.1 dB reduction in (RF signal) attenuation can increase PA efficiency by about 1% or equivalent to 10 mA reduction of current drain fir a cell phone with a 28 dBm output. Further, a relaxed design of the transmit filter (130) can also allow for fewer stages in the design of the filter, thus fewer components for a reduction in effective size of the filter. According to further embodiments of the present disclosure and due to the relaxed design requirements of the transmit filter (130), such filter can be designed using standard RLC filter design techniques known to the skilled person, and therefore providing some cost benefits over the typical SAW/BAW filter implementation as well as possibility for monolithic integration of the filter within a duplexer integrated circuit (IC) or other.
A typical range for the gain of the final amplifier stage (160) can be 10-20 dB. A typical noise figure of the final stage can be less than 10 dB.
Attenuation at the receive frequency band per the various embodiments of the present disclosure can be performed by the filter (270) as depicted in
Similar to
As previously mentioned, a transmit/receive RF signal can be in correspondence of a frequency band associated to a wireless standard (e.g. mode), and in turn, the frequency band can comprise a plurality of channels which can be used to transmit/receive an RF signal according the defined modulation scheme of the wireless standard. As it is known by the person skilled in the art, a same transmit/receive system, such as one depicted in
The system block diagram according to an embodiment of the present disclosure depicted in
The tunable filters described in the various embodiments according to the present disclosure can be constructed using one or more variable reactive elements, such as variable capacitors and variable inductors. Digitally tunable capacitors (DTC) and/or digitally tunable inductors, as described in, for example. International Application No. PCT/US2009/001358 and U.S. patent application Ser. No. 13/595,893, whose disclosures are incorporated herein by reference in their entirety, can also be used in constructing such tunable filters (e.g. low-pass, high-pass, band-pass, band-reject, notch, etc. . . . ). The person skilled in the art readily knows how to realize such tunable filters and how to select components with values (e.g. ranges of values) consistent with a desired filter characteristics (e.g. to provide a desired frequency response). Tuning of such tunable filter can comprise varying a value of one or more of its variable reactive elements under control of a signal-aware processor as discussed in the prior sections of the present disclosure.
As previously mentioned, the various exemplary embodiments of the present disclosure are not limited to a transmit path with an amplification stage comprising two amplifiers (150, 160), and transmit/receive systems with amplification stages in their transmit paths comprising more than two amplifiers can also benefit from the teachings of the present disclosure. According to an exemplary embodiment of the present disclosure, more than one, such as two or more, tunable filters (270) can be placed in various inter-stage locations of an amplification stage comprising more than two amplifiers (e.g. stages). Such configuration can allow attenuation of the transmit channel noise over a same frequency band corresponding to a receive signal at various points in the transmit path, with a net effect of reducing overall noise at the output of the transmit path. As the number of amplifier stages increases, amplification of the noise also increases, and therefore an increased number of filters (270) at various points of the transmit path can be desirable.
According to another embodiment of the present disclosure, the tunable filter (270) can be monolithically integrated with the driver (150) and/or with the final amplifier (160). Monolithic integration of the amplification stage (e.g. comprising driver (150) and final (160)) can be desirable because it provides, for example, matching between devices (e.g. transistors used in the amplifiers) to track and adjust variations due to manufacturing tolerances, temperature and others in ways not possible across multiple integrated circuits, such as, for example, described in the referenced U.S. patent application Ser. No. 13/797,779 and U.S. patent application Ser. No. 13/967,866, whose disclosures are incorporated herein by reference in their entirety. Other benefits of monolithic integration can include better overall performance of the integrated devices due to shorter traces as well as reduced manufacturing cost, assembly cost, testing cost and form factor. It follows that, according to an embodiment of the present disclosure, such monolithically integrated amplification stage (e.g. 150 and 160) can also include the (tunable) filter (270). Furthermore, a duplexer unit (130) comprising RLC filters such as per the relaxed design embodiments provided by the teaching according to the present disclosure, can also be monolithically integrated, entirely or partially, together with other components such as (150), (160) and (270) of the transmit/receive communication system (200) of
The examples set forth above are provided to give those of ordinary skill in the art a complete disclosure and description of how to make and use the embodiments of the present disclosure, and are not intended to limit the scope of what the inventors regard as their disclosure. Modifications of the above described modes for carrying out the disclosure may be used by persons of skill in the art, and are intended to be within the scope of the following claims. All patents and publications mentioned in the specification may be indicative of the levels of skill of those skilled in the art to which the disclosure pertains. All references cited in this disclosure are incorporated by reference to the same extent as if each reference had been incorporated by reference in its entirety individually.
It is to be understood that the disclosure is not limited to particular methods or systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used in this specification and the appended claims, the singular forms “a”. “an”, and “the” include plural referents unless the content clearly dictates otherwise. The term “plurality” includes two or more referents unless the content clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure pertains.
A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the present disclosure. Accordingly, other embodiments are within the scope of the following claims.
Claims
1. A radio frequency (RF) circuital arrangement comprising:
- an RF transmit path comprising: a plurality of cascaded amplifiers configured, during operation of the circuital arrangement, to amplify a transmit RF signal, the transmit RF signal operating over a first frequency band, and a first filter placed between two consecutive amplifiers of the plurality of cascaded amplifiers, the first filter configured during operation of the circuital arrangement, to attenuate a second frequency band different from the first frequency band, and pass the first frequency band:
- an RF receive path configured, during operation of the circuital arrangement, to receive a receive RF signal over the second frequency band, and
- a bi-directional transmit/receive circuit connected to the RF transmit path and to the RF receive path, the bi-directional transmit/receive circuit comprising: a second filter configured, during operation of the circuital arrangement, to pass the first frequency band and to attenuate the second frequency band.
2. The RF circuital arrangement of claim 1, wherein:
- an attenuation over the first frequency band provided by the first filter is less than about 5 dB, and
- an attenuation over the second frequency band provided by the first filter is greater than about 10 dB.
3. The RF circuital arrangement of claim 1 or claim 2, wherein an attenuation over the second frequency band provided by the combination of the first filter and the second filter is greater than about 35 dB.
4. The RF circuital arrangement of claim 1, wherein, during operation of the circuital arrangement, the hi-directional transmit/receive circuit is configured:
- to provide an amplified version of the transmit RF signal from the RF transmit path to a transmit/receive antenna, and
- to receive the receive RF signal from the transmit/receive antenna and provide said signal to the RF receive path.
5. The RF circuital arrangement of claim 1, wherein the first frequency band and the second frequency band are in correspondence of a mode of operation of the circuital arrangement, and wherein the circuital arrangement is configured, during operation of the circuital arrangement, to operate in one of a plurality of modes of operation comprising a plurality of different first frequency band and second frequency band.
6. The RF circuital arrangement of claim 5, wherein the first filter is a tunable tilter configured, during operation of the circuital arrangement, to be tuned to attenuate a second frequency band and pass a first frequency band in correspondence of a mode of operation of the plurality of modes of operation of the circuital arrangement.
7. The RF circuital arrangement of claim 6, wherein the first filter and the second filter are RLC type filters.
8. The RF circuital arrangement of claim 6, wherein the first tilter is an RLC type filter.
9. The RF circuital arrangement of claim 3, wherein the first filter and the second filter are RLC type filters.
10. The RF circuital arrangement of claim 1, wherein the first filter comprises one or more of: a) a digitally tunable capacitor, and b) a digitally tunable inductor.
11. The RF circuital arrangement of claim 7, wherein the first filter comprises one or more of: a) a digitally tunable capacitor, and b) a digitally tunable inductor.
12. The RF circuital arrangement of claim 7, wherein the first filter is one of: a) a low-pass filter, b) a high-pass filter, c) a band-pass filter, d) a band-stop filter, and e) a notch filter.
13. The RF circuital arrangement of claim 1, wherein the first filter is one of: a) a low-pass filter, b) a high-pass filter, c) a band-pass filter, d) a band-stop filter, and e) a notch filter.
14. The RF circuital arrangement of any one of claims 1, 2, or 7, wherein the bi-directional transmit/receive circuit is a duplexer circuit comprising the second filter, and wherein the second filter is designed with relaxed parameters, wherein the relaxed parameters reduce a number of filter stages of the second filter.
15. The RF circuital arrangement of claim 14, wherein the reduced number of filter stages of the second filter provide a reduced attenuation of the second filter in the first frequency band.
16. The RF circuital arrangement of claim 15, wherein the reduced attenuation of the second filter in the first frequency band is less than about 2 dB.
17. The RF circuital arrangement of claim 14, wherein the duplexer circuit further comprises a third filter coupled to the receive path and configured, during operation of the circuital arrangement, to pass the second frequency band.
18. The RF circuital arrangement of claim 1, wherein the plurality of cascaded amplifiers and the first filter are monolithically integrated.
19. The RF circuital arrangement of claim 7, wherein the plurality of cascaded amplifiers and the first and/or second filter are monolithically integrated.
20. The circuital arrangement of claim 9, wherein the plurality of cascaded amplifiers and the first and/or second filter are monolithically integrated.
21. The RF circuital arrangement of claim 1, wherein the plurality of cascaded amplifiers comprises a first amplifier configured to receive the RF transmit signal into the plurality of cascaded amplifiers, and a last amplifier configured to output an amplified version of the RF transmit signal by the plurality of cascaded amplifiers, and wherein the first filter is configured to attenuate an amplified noise figure at the second frequency band.
22. The RF circuital arrangement of claim 1, further comprising one or more filters similar to the first filter, the one or more filters placed between one or more two consecutive amplifiers of the plurality of amplifiers, the one or more filters and the first filter not being directly connected, wherein the one or more filters are configured during operation of the circuital arrangement, to attenuate the second frequency band and pass the first frequency band.
23. The RF circuital arrangement of claim 1, wherein the plurality of cascaded amplifiers comprises a driver amplifier and a final amplifier, and wherein the first filter is placed between the driver amplifier and the final amplifier.
24. A communication device for bi-directional transmit and receive of RF signals, the communication device comprising the RF circuital arrangement of claim 6.
25. The communication device of claim 24 further comprising a transceiver unit, wherein during operation of the communication device, the transceiver unit is adapted to tune the tunable filter according to the mode of operation.
26. A method for reducing loss of a transmit RF signal in a duplexer unit of an radio frequency (RF) transmit/receive system, the method comprising:
- providing an RF transmit path comprising a plurality of cascaded amplifiers;
- inserting, in-between two amplifiers of the plurality of cascaded amplifiers, a first filter;
- based on the inserting, attenuating a receive frequency band and passing a transmit frequency band:
- based on the attenuating, relaxing design parameters of a second filter of a duplexer unit, the second filter being configured to pass the transmit frequency band and to attenuate the receive frequency band;
- based on the relaxing, reducing a number of filter stages of the second filter, and
- based on the reducing, reducing an attenuation at the transmit frequency band through the second filter of the duplexer unit.
27. The method of claim 26, wherein the plurality of cascaded amplifiers comprises two amplifiers; a driver amplifier and a final amplifier, and wherein the first filter is inserted between the driver amplifier and the final amplifier.
28. The method of claim 0 or claim 27, further comprising:
- coupling the second filter of the duplexer unit at an output of the plurality of cascaded amplifiers of the RF transmit path;
- based on the coupling, isolating an RF receive path operating at the receive frequency band from a signal at the output of the plurality of cascaded amplifiers, the RF receive path being coupled to a third filter of the duplexer unit, and
- based on the coupling, reducing an attenuation of a transmit RF signal via the RF transmit path.
29. The method of claim 28, wherein the duplexer unit is coupled to a transmit/receive antenna, and wherein the duplexer unit is configured to receive an RF signal at the receive frequency hand and feed said RF signal to the RF receive path.
30. The method of claim 28, wherein the third filter is configured to pass the receive frequency band and to attenuate the transmit frequency band.
31. The method of claim 26, wherein the first filter is a tunable filter.
32. The method of claim 31, further comprising:
- selecting a different receive frequency band and transmit frequency band, and
- based on the selecting, tuning the first filter to attenuate the different receive frequency band and pass the different transmit frequency band,
- wherein the second filter is configured to pass the different transmit frequency band and attenuate the different receive frequency band.
33. The method of claim 32, wherein the selecting is in correspondence of a desired mode and/or channel of operation from a plurality of modes and/or channels of operation of the RF transmit/receive system, and wherein the second filter is configured to pass a plurality of transmit frequency hands and attenuate a plurality of receive frequency bands in correspondence of the plurality of modes and/or channels of operation of the RF transmit/receive system.
34. The method of claim 32, wherein the tuning is performed by a controller unit aware of the different receive and transmit frequency bands.
35. The method of claim 34, wherein the selecting and the tuning is performed by a transceiver unit of the RF transmit/receive system.
36. The RF circuital arrangement of claim 26, wherein the second filter is an RLC type filter.
37. The RF circuital arrangement of claim 26, wherein the first and the second filter are RLC type filters.
38. The RF circuital arrangement of claim 31, wherein the first filter comprises one or more of: a) a digitally tunable capacitor, and b) a digitally tunable inductor.
39. The RF circuital arrangement of claim 37, wherein the first filter is one of: a) a low-pass filter, b) a high-pass filter, c) a band-pass filter, d) a band-stop filter, and e) a notch filter.
Type: Application
Filed: Feb 14, 2014
Publication Date: Aug 20, 2015
Applicant: PEREGRINE SEMICONDUCTOR CORPORATION (San Diego, CA)
Inventor: Dan William Nobbe (Crystal Lake, IL)
Application Number: 14/181,489